Video recording is a standard feature for cameras, smart phones, tablets and many other devices. Compact cameras and mobile devices such as phones and tablets are usually equipped with smaller size image sensors and less than ideal optics. Video denoising is especially important for these devices. High-end cameras and camcorders are generally equipped with larger size image sensors and better optics. Captured videos using these devices have decent quality under normal lighting conditions. However, videos recorded under low light conditions still demand significant improvement even for high-end cameras and camcorders. In addition, many recording devices have increased their resolutions in recent years (e.g., from SD to HD, from HD to 4K, and maybe 4K to 8K in the future). Increased video resolution lowers the signal-to-noise ratio at every pixel location on the image sensor. Video denoising becomes even more challenging with increased video resolution.
Many methods were proposed to address video denoising including “A method to improve video quality under low light conditions” as described in U.S. patent application Ser. No. 14/669,433, filed on Mar. 26, 2015. Utilizing an entire video frame for video denoising requires large computation power and storage space since both single-frame denoising and difference-frame denoising results are calculated and stored. Therefore a more efficient video denoising method in both computation power and memory usage is being demanded.